This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A158298 #20 Jul 17 2019 03:18:07 %S A158298 1,2,1,1,1,2,1,4,3,2,1,1,1,2,1,5,1,6,1,1,1,2,1,4,1,2,1,1,1,2,1,2,1,2, %T A158298 1,3,1,2,1,4,1,2,1,1,3,2,1,1,1,2,1,1,1,2,1,4,1,2,1,1,1,2,3,7,1,2,1,1, %U A158298 1,2,1,12,1,2,1,1,1,2,1,5,5,2,1,1,1,2 %N A158298 Denominators of averages of squares of the divisors of n. %C A158298 Average of squares of the divisors of n = A001157(n)/A000005(n). %C A158298 Iff a(n) = 1, n is in A020486. %H A158298 Amiram Eldar, <a href="/A158298/b158298.txt">Table of n, a(n) for n = 1..10000</a> %t A158298 Array[Denominator[DivisorSigma[2, #]/DivisorSigma[0, #]] &, 100] (* _Amiram Eldar_, Jul 15 2019 *) %o A158298 (PARI) a(n) = denominator(sigma(n, 2)/numdiv(n)) \\ _Michel Marcus_, Jun 13 2013 %Y A158298 Cf. A001157, A000005, A020486, A158299 (for numerators). %K A158298 nonn,frac %O A158298 1,2 %A A158298 _Jaroslav Krizek_, Mar 15 2009 %E A158298 Data corrected and extended by _Amiram Eldar_, Jul 15 2019